However, [1]} suggested that the fossil status may be only a transitional phase in the life of a regular cluster. If this is the case, there is no need to find a special category of progenitors, since the acquisition of the fossil status could happen to any group/cluster in the period between the last major merger and the subsequent arrival of another bright galaxy from the cosmic web. We will discuss this topic from an observational point of view in the second part of this section.
